PURPOSE: To prevent wrinkles in a back plate from developing by a method wherein burrs developed by cutting the iron blank of a front plate are located at the inside of the end part of the bent parts of the front plate during the manufacture of a floor heating panel.

CONSTITUTION: Firstly, burrs 1d developed by cutting an iron blank in order to form a front plate 1 are located at the inside of the end part of the bent parts 1c of the front plate 1. Secondly, the front plate 1 is placed upsidedown onto a press platen 6 and at the same time a back plate 4 is placed onto the bent parts 1c of the front plate 1. Thirdly, a press platen 5 is placed onto the back plate 4 so as to pinch the front plate 1 and the back plate 4 with the press platens 5 and 6. Heat insulating material 7 such as urethane foam or the like is filled in a space formed by the front plate 1 and the back plate 4 as indicated with the arrows. During the filling of the heat insulating material 7, the end part of the bent part 1c and the back plate 4 slide smoothly each other, resulting in developing no wrinkle in the back plate 4.